Piston and piston ring



'May 15, 1945. H. B; JOHNSTON PISTON AND PIST ON RING Filed April 29. 1942 2 Sheets-Sheet l moorland M M T. W n mp m 0 Wu Wu 3 g H m provision of an improved piston Patented May 15, 1945 This invention relates to pistons and piston rings and has particular relation to a ring which is expanded primarily by the end of the cyl inden' i In internal combustion motors, itis veryimporta'nt that the piston rings not only hold tightly' to restrain the gases from passing the piston but upon release of thepressure at the end of a stroke, to have the ring release-its pressure and yet remain free in its grooveready for instant sealing action when pressure is again applied. This is particularly true in internal combustionmotors of the'Diesel or semi-Diesel type where in the'past'great difficulty has been experienced in keeping'the piston rings free."

The primary object of this invention is the ring ,for a rectangular groove which will expand'a' inst the cylinder wall. in direct proportion to the fluid pressure at the piston head. I

Another Object of the nvention is the pro'-' vision of a piston ring having coacting circular sections, one of which, in operation, presses against the inner or back wall of the groove while another ring section presses against the cylinder wall to seal the space at the cylinder wall at the's'ametime, the ring sections being so constructed that they will make a sealbetween each other to prevent the passage of fluids th'erebetween. i

A further object of the invention is the provision of a piston; ring having. a pair of singlesplit coacting circular ring sections, one section operating to seal the cylinderwall and piston.

against thepassage of fluids in one direction while the other section is against the back wall of the groove, thetwo gular groove.

A still further object of the invention is the sections filling a rectanprovision of a piston ringcomposed of a pair of single-split ring sections having coacting conical surfaces, one section having an inner surface of normal diameter, approximately equal to the diameter of the inside or back wall of arectan gular groove of a piston to normally seat thereon, the outside faces of thejring sections bein in respective plans to fit side walls of the groove.

Another and still further object of the inventionis'the provisionpf a ring and groove con-- Another and still further objectof the invcntion is the provision of a piston ring for a piston ring groove of the rectangular cross section type, the ring having oppositely disposed plane 'surfaces and composed of a pair ofsingle-split circular ring sections, one of the ring sections having a conical'surface and inner cylindrical surface'normally' in contact at all times with the back or inner wall of the groove, the other ring section having a normally outwardly expanding tendency and. having a conical surface in cooperative contact with the conical surface of the'other ring section, the oppositely disposed plane surfaces normally being adjacent to or in contact with the opposite plane walls of the rectangular groove.

Other and further objects of the invention will be apparent to those Skilled in the art from a reading of the complete specification.

Referring to -the drawings, wherein the invention is illustrated, v

Fig. '1 is a partial sectional View of a piston and ring embodying my invention.

' scale than Fig. 1.

Fig, la. is a detail view of the ring on a larger Fig. 2 is a side view of the ring as a whole, parts being shown in sections.

Fig. 3 is a view similar to Fig. ring sections separated.

'Fig. 4 is a view similar to Fig. 1 but of a modified form of the invention. I Fig. 5 is a view similar to Fig.2 but ofthe ring ofthe modified form shown in Fig. 4. r

Fig. 6 is a view similar to Fig.1.3lbut ofqthe ring of the modified form illustrated in Fig. 4.

I Fig. '7 is a sectional view similar to Fig. 1 but of a still further modified ring construction.

In describing the invention, similar reference characters refer to the same or similar parts throughout the specification and drawings.

Referring particularly to Figs. 1 to 3 inclusive Ill designates the head of .a piston having a side wall ll and a groove I2. .The groov I2 is of of the cylinder within which the piston operates tangular ring comprising lower section I is provided as-will be described;

-' Within the groove 12 is a substantially rectwo sections. The with an inner substantially cylindrical surface mal diam'eternot greater than the inner or back 2 but with the t l 5 which has a nor? wall I of the groove I2. The surface I5 is preferably of a diameter slightly less than the diameter of the inner wall I6 of the groove I2 in order that a very slight inward tension of the ring section I4 will hold it to its seat.

The plane surface I I of the ring section I4 is in contact with the plane side wall I8 of the groove I2. The outer narrow cylindrical face I9 of the ring section I4 is substantially flush with the periphery of the piston.

On oneside of the ring section I4 is a tapered or conical surface which coacts with a similarly shaped tapered or conical surfac 2I of the ring section 22.

This ring section 22 preferably has an outward resiliency tending to normally press itsouter cylindrical surface 23 against the wall of the cylinder 24. The inner side of the ring section .22 is shown as a cylindrical surface 25 and the other surface 26 is plane and normally in contact with oradjacent the side wall 21 of .the groove I2.

The rin section I4 is preferably beveled at the junction of the surfaces I5 and IT as shown in Fig.1 at v20. This feature assists in making tight installations in old piston grooves where the wall I8 -may have been slightly worn.

In operation, the fluid pressure contacts the surface .25 by passing the cut away space I3. This pressure coming in contact with the sur face 26, causes a tendency of thering section 22 to be forced outwardly against the cylinder wall. At the same time, the tapered or. conical surfaces 20, 2|, coact .to tend-toforce the ring section I4 against "the inner or back wall I6 and the side wall I0 of. the groove I2. Since the ring section I4 is normally against the wall I0, there will :be no movement but a tight seal will be effected. Thus is prevented the passage of the .fiuid (1) outside of the ring, (2) insi decf the ring and (3) between thering sections-due tothe coaction of the conical surfaces.

An advantage of this construction is that an installation may be made in an old .piston where the groove is larger than when made, and even though there may be a slight play, the tolerance is greater than with the usual rectangular construction.

The modification of Figs. 4, '5 and 6 has a piston head I0 of piston II, with a rectangular groove I2 to receive the ringto be described. A cut away portion I3 allows fluid pressure to readily reach the ring. I r

In this modification as shown in detail'in Fig. 4, the ring sections I 00 and I01 have a pair of similar and coacting tapered or conical surfaces I02 and I03 which cooperate to prevent the passage of fluid pressure between the ring sections The ring section 1:00 has an inner cylindrical surface I0 4 which contacts with a similarly shaped innerwall I 6 of the groove IJ2. The diameterof-the cylindrical wall Iii-relative to that of the inner surface 'IEM of the ring I00, is such that the ring has a normal position againstthe inner wall of'the groove. In .other'words,the diameter of the :cylindrical surface I04 is not greater-than the diameter of the inner or back wall .1 0 ofthe groove and is preferably slightly less.

Adjacent the wall I8 of the groove 12, the ring section I00 has a plane surface 105, with which it is normally in contact or to which *it-is closely adjacent. The :radial thickness of the ring section I00 is such that its outer-cylindricalsurface I06 does not extend beyond the periphery of the piston II.

Between "the surfaces I02 and I06, is a surface cylinder 24. A surface IIU extends between the surfacesIIlZ and I09 and opposite the surface I01 of the-ring section I00. This surface H0 is normally out .of contact with the surface I0'I but the space therebetween furnishes a convenient pocket foruoil to collect when the piston is making its downward stroke as shown in Fig. 4. As the piston reverses its movement, the oil is again spread on the cylinder wall. During the stroke downward as seen in Fig. 4, the'oil is driven down by the ring and is not blown out by the fluid I pressure-since it is tightly held by the tapered surfacesbetween the ring sections and the contactsbetween the surfaces I04 and I09 with the groove wall I6 and the cylinder wall 24, respectively.

A beve ed edge "III between the surfaces I04 and-'I05-a1lowsfor a filet between the groove walls I8 and I6, thus permitting the installation :to be made in old pistons and where the wall I8 may have been worn. Inspite of this wear, greater tolerance is possible without any sacrifice in the sealing quality of the ring.

The ring section ILIlI has an outer or top surface H2 which engages the groove wall 12! and. holds :the ring sections in relative operative position. It is this surface ;I:=I2 which is primarily exposed to the fluid pressure which enters through the cut away portion I3 of the'h'ead.

In operationyas the fluid pressure forces downw-arclly ont'hesu'rface I I2 :o'f'the ring section Isl, as shown in Fig-4, the :coaction "between the surfaces If02and I03, tends to contract the ring section I00 and exp'andthe ring section .120 I. As the ring section I200 tends 'zto'contract, the surfaces I04 and I 05.are :forced against the walls I6 and I8, respectively, of the groove I 2. 'The tendency for the ring section I DI to move outwardly against thev cylinder wall 24 prevents the fluid :passage between the ring and cylinder "wall. 'Thus, the passage of the fluid pressure is prevented 'by ('1) the coaction between the tapered or conical surfaces 'I;02 all-d103, ('2) the passage'behi nd the ring section and (3') between the ring section IOI and the cylinderwall '24.

In Fig. 7 is a further modification wherein two ring sections '200, 20I have cooperating tapered or :conical surfaces 202, 203.

The ring section "200 has an inner cylindrical surface 204 which contacts with the wall 16 of the groove I2 and a flat surface 205 which contactswith the wall I6 of the groove. "This section .200 also has a cylindrical surface 200 extending from the tapered surface -202 "and a narrow surface 201 opposite the surface "2'05.

The section 20I has a flat surface 2! opposite the groove wall 1:8, .anouter cylindrical surface 2H for contact with the cylinder wall 2:4. It also has a fluid-pressure receiving surface :212 which is held in place :by the groove surface 121. There is also an inner surface 203 between the surfaces1202 and 2 I2.

The modifications in Figs. 4, 5, 6 and 7 are particularly useful where relatively low pressures are used in the cylinder.

1. In combination, a piston having a groove and being cut away between its end and the adjacent wall of the groove and a piston ring comprising two sections, each section having a single split and a conical surface coacting with a similar conical surface of the othersection, one of .the sections having an outwardly tapering cross section having a substantially plane surface in I contact with a similarlyshaped wall of the groove and having a cylindrical surface for normal conto be' compressed to within the periphery of the piston.

3. In combination, a piston having a circumferential groove of substantially rectangular cross section and being cut away between its head and the adjacent wall of the groove, a piston ring comprising two sections, each having a single split and a conical surface coacting with a similar conical surface of the other section, oneof the sectionshaving an outwardly tapering cross section having a substantially plane surface in contact with a similarly shaped wall of the groove and having an inner cylindrical surface for normal contact with the inner or back wall of a piston groove and being of a normal diameter not greater than the diameter of the said inner or back wall, the other section having an inwardly tapering cross section having an outer cylindrical surtact with the back or inner wall of the groove, the

other section having an inwardly tapering cross section having an outer cylindrical surface for contact with the cylinder in which the piston is to operate, the radial thickness of each section being'n0t greater than the radial depth of the groove and of a size tobe compressed to within the'periphery of the piston.

face for contact with the cylinder in which the piston is to operate, the radial thickness of each section being not greater than the radial depth of the groove and of a size to be compressed to within the periphery of the piston.

4. In combination, a piston having a circumferential groove of substantially rectangular cross I section and having a portion cut away between 2. In combination, a piston having a circumferential groove of substantially rectangular cross section and being cut away between its head and the adjacent wall of the groove, a piston ring comprising two sections, each having a single split and a conical surface coacting witha'similar conical surface of the other section, oneof the sections having an outwai'rdly tapering cross section having a substantially plane surface in contact with a similarly shaped wall of the groove and having an inner cylindrical surface for normal contact with the inner or back wall of a piston groove, the other section having an inwardly tapering cross section having an outer cylindrical surface for contact with the cylinder in which the piston is to operate, the outer section having a greater radial width than axial width, the radial thickness of each section being not greater than the radial depth of the groove and of a size the piston end and the groove, a piston ring comprisin two sections, each having a single split and a conical surface coacting with a similar con ical surface of the other section, one of the sections having an outwardly tapering cross section .having a substantially plane surface in contact with a similarly shaped wall of the groove and having an inner cylindrical surface for normal contact "with the inner or back wall of a piston groove and being of a normal diameternot greater than the diameter of the said inner or back wall, the other section having an inwardly tapering cross section having an outer cylindrical surface for contact with the cylinder in which the pistonis to operate and having a normal outward resilient pressure for keeping a constant pressure against the cylinder wall, the radial thickness 7 of each section being not greater than the radial depth of the groove and of a size to be compressed to within the periphery of the piston.

HARRY B. JOHNSTON. 

